Explosion apparatus for flanging a tube



N 1 c. E. FRANTZ ETAL EXPLQSION APPARATUS FOR FLANGING A TUBE Filed Jan. 5, 1964 H N Q Wm kw NW N.

\w \m .3 Q. g I) United States Patent 3,287,947 EXPLOSION APPARATUS FOR FLANGING A TUBE Charles E. Frantz, Richland, Wash., William E. Cawley, Phoenix, Ariz., and Frank F. Vlacil and Eugene R. Astley, Richland, Wash, assignors to the United States of America as represented by the United States Atomic Energy Commission Filed Jan. 3, 1964, Ser. No. 335,699 3 Claims. (Cl. 72-56) The invention described herein was made in the course of, or under, a contract with the US. Atomic Energy Commission.

This invention relates to an apparatus for flanging a tube. More specifically, the invention relates to an apparatus in which gases generated by an explosion are used to form a flange on a tube end and force the flange into tight sealing engagement with a member surrounding the tube end.

Figs. 37-39 and columns 42-44 of Fermi et a1. Patent 2,708,656, dated May 17, 1955, disclose a nuclear reactor in which coolant tubes containing nuclear-fuel slugs extend through a graphite pile and have their ends connected to opposed faces of the reactor. For various reasons having to do with reactor operation, it may be desirable to form flanges on the tube ends and seal the flanges to tubular members that contain the tube ends and are located in the reactor faces.

The flanges may be formed by rolling, but rolling produces severe work-hardening, which induces cracks and early failure of the flanges. The flanges may also be produced by a curved die propelled axially of the tube by an explosion, but undesirable thinning of the tube at the corner joined to the flange being formed and loosening of the flange at the other end of the tube have resulted with the use of such a die.

In the drawings:

FIG. 1 is an exploded elevational view of the novel flan ging apparatus of the present invention;

FIG. 2 is a longitudinal sectional View showing the flanging apparatus applied to a tube that is to be flanged;

FIG. 3 is a fragmentary sectional view similar to FIG. 2 showing the forming of a flange on the tube end; and

FIG. 4 is a fragmentary sectional view of a nuclear reactor.

As shown at the left in FIG. 1, a gun is used with the flanging apparatus of the present invention, which gun has a threaded connection with a body 11. The body has at the end adjacent the gun 10, an explosion chamber 12 which is provided with a flared open end 13 and an opposite end from which extends a plurality of generally radial passages 14, only one of which is shown in FIGS. 2 and 3. The passages 14 open into a peripheral groove 15 formed on the exterior of the body 11.

The body 11 has adjacent the end where the explosion chamber 12 is located, an external flange 16 with which a die 17 has a threaded connection. The die 17 clamps against the flange 16 an external flange 18 formed on one end of a flexible, resilient, expansible sleeve 19, which may be formed of neoprene rubber. The sleeve 19 embraces the body 11 and has an internal rib 20 fitting the groove 15 of the body 11. At the end of the sleeve 19 opposite the flange 18, there is an internal flange 21, which is received in an external groove 22 formed on the body 11 near the end opposite the end where the explosion chamber 12 is formed.

Beyond the sleeve 19 the body 11 has a threaded connection with the interior of an end portion 23 of a mandrel 24. The mandrel has an internal shoulder 25 engaging the end of the sleeve 19 where the flange 21 is located. Beyond the shoulder 25 the mandrel 24 has a portion 26-, which extends for a major part of the length ice of the mandrel, is longitudinally slotted and relatively thin, and embraces the sleeve 19. The portion of the sleeve 19 embraced by the mandrel 24 extends to a region adjacent the internal rib 20 and the groove 15 where the passages 14 of the body 11 terminate.

The embraced portion of the sleeve 19 is a little thinner than the remainder of the sleeve so that the assembled sleeve and mandrel 24'present an exterior of uniform diameter and so may readily fit in a tube 27 which is to be flanged. This tube may be an aluminum coolant tube used in a reactor as disclosed in Figs. 37-39 and columns 42-44 of Fermi et a1. Patent 2,708,656, dated May 17, 1955, to contain nuclear fuel elements (not shown) that are to be cooled by water flowing through the tube. The tube 27 has two internal longitudinal peripherally spaced ribs 28 at its bottom, one rib being shown in FIGS. 2 and 4, for supporting the fuel elements. The mandrel 24 has two external longitudinal grooves 30, one being shown in FIG. 1, to accommodate the ribs 28 in the tube 27. At the thin portion 26 of the mandrel 24, the grooves 30 become slots. As shown in FIG. 4, the tube 27 extends through a graphite pile 31 of a nuclear reactor and walls 32 at the end faces of the reactor. The tube 27 has its end portions in tubular members 33 mounted in and sealed to the walls 32. The tube 27 has at its ends flanges 34 which are sealed to the ends of the tubular member 33 by virtue of the pressure between the flanges and the tubular member. One of the tube flanges 34, for example, the one at the right as viewed in FIG. 4 is preformed before the tube 27 is installed in the reactor.

When the left-hand flange 34 is to be formed, the apparatus is positioned in the tube 27, as shown in FIG. 2, the sleeve 19 and the mandrel 24 engaging the interior of the tube 27, and feet 35 of the die 17 resting against the end of the tubular member 33 against which the flange 34 is to be formed. The feet 35 on the die 17 are peripherally spaced and are four in number. The die 17 has an arcuate recess 36 to accommodate an expanded portion of the sleeve 19 as it is pushing the flange 34 against the end of the tubular member 33. The spaces between the feet 35 permit air in the recess 36 to escape as the sleeve is expanded into the recess.

A blank cartridge 37 of the exploding type, but with the shot or bullet removed, is placed in the chamber 12 and held there by a retractable bolt 38 of the gun 10. An ordinary blank is not used, but rather a progressively burning propellant charge such as might be used for live ammunition. When the gun is fired, a firing pin 39 is released or projected through the bolt 38 against the cartridge 37 to flre the same. The gas generated by the firing can escape from the chamber 12 only through the passages 14 in the body 11. As shown in FIG. 3, the gas generated expands the sleeve 19 away from the body 11, with the two results, that the mandrel 24 is pushed outward into tight engagement with the tube 27, and that the sleeve 19 is forced out into the recess 36 in the die 17 while forming the flange 34. At the outset, when the end of the tube '27 is first being forced outward by the sleeve 19, the force applied is essentially radial. An axial reaction is present only when the tube flange 34 starts to turn. This gives a time interval for the tube 27 to be securely gripped by the mandrel 24 because of the expansion of the sleeve 19 against the mandrel due to gas generated by the firing, before a significant axial force is present. There is no thinning of the tube 27 during the forming of the flange 34, because there is no axial movement of the expanding sleeve 19 or the mandrel 24. These members move radially outward only; only the gas generated moves lengthwise of the tube. The gas mass is so low that no discernible reaction results from the firing in the present apparatus. The noticeable result of 3 firing is a low pop and hiss of escaping gas. There is no kick or shock.

The sleeve 19 can expand outwardly to any appreciable degree only at the recess 36 in the die 17, since the sleeve 19 fits the die 17 except at the recess 36, as well as fitting the tube 27 and the sleeve 19. Thus, the expansion of the sleeve 19 is concentrated in the recess 36 and is sufficient to form the flange 34 against the end of the tubular member.

The peripheral groove 15 is provided on the body 11 so that the gases generated in the explosion chamber 12 and escaping therefrom through the passages 14 are applied uniformly about the interior of the sleeve 19 so that the forces to form the flange 34 are applied uniformly around the interior of the tube 27. The internal rib 20 in the sleeve 19 is provided to fill the groove 15 so that the space composed of the chamber 12 and passages is kept to a minimum and thus the gases generated :by the firing of the cartridge 37 can act effectively to expand the sleeve 19.

When the left-hand flange 34 is formed, there is no reaction by the apparatus of the present invention against the tube 27 such as would loosen the engagement of the right-hand flange 34 with the associated tubular member 33. Both flanges 34 have sealing engagement with the tubular members 33. Sealing at these locations is important, because it prevents the reactor atmosphere, i.e., that between the walls 32 in the graphite pile 31, from escaping through the annuli between each coolant tube 27 and the tubular members 33. A suitable formation of the left-hand flange 34 is important, because the flange itself forms part of a seal between the tube 27 and the nozzle (not shown) of a charging machine attached thereto for supplying new fuel elements to the tube 27.

The gun 10 may be the action or active portion of the Model 1903-A3 Springfield army rifle. The bolt 38 may have hook-like parts (not shown) engageable with the flange on the closed end of the cartridge 37. Thus, the

bolt, on being retracted, pulls the fired cartridge out of the chamber 12.

The intention is to limit the invention only within the scope of the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A tube-flanging apparatus comprising a central body having a longitudinal explosion chamber extending from one end of the body and terminating at a region spaced from said one end in generally radial passages extending to the outside of the body, the body having an external flange near the said one end and an external groove near the other end, an expansible flexible sleeve embracing the body and having an external flange at one end engaging the external flange on the body and an internal flange on the other end engaging the groove on the body, means for holding the flanges of the body and the sleeve together, a mandrel connected to said other end of the body, engaging said other end of the sleeve, and embracing said sleeve from said other end thereof to a region thereof adjacent the portion of the body in which the said passages are located.

2. The apparatus of claim 1, the body having an external groove in which the passages terminate, the sleeve having an internal rib engaging the groove.

3. The apparatus of claim 2, the means for holding the flanges of the :body and sleeve together being a die adapted to react against a part against which the tube is to be flanged, the die embracing the sleeve except at a recess surrounding the sleeve just beyond the said part.

References Cited by the Examiner UNITED STATES PATENTS 3,127,923 4/1964 Cadwell 72-56 CHARLES W. LANHAM, Primary Examiner.

RICHARD J. HERBST, Examiner. 

1. A TUBE-FLANGING APPARATUS COMPRISING A CENTRAL BODY HAVING A LONGITUDINAL EXPLOSION CHAMBER EXTENDING FROM ONE END OF THE BODY AND TERMINATING AT A REGION SPACED FROM SAID ONE END IN GENERALLY RADIAL PASSAGES EXTENDING TO THE OUTSIDE OF THE BODY, THE BODY HAVING AN EXTERNAL FLANGE NEAR THE SAID ONE END AND AN EXTERNAL GROOVE NEAR THE OTHER END, AN EXPANSIBLE FLEXIBLE SLEEVE EMBRACING THE BODY AND HAVING AN EXTERNAL FLANGE AT ONE END ENGAGING THE EXTERNAL FLANGE ON THE BODY AND AN INTERNAL FLANGE ON THE OTHER END ENGAGING THE GROOVE ON THE BODY, MEANS FOR HOLDING THE FLANGES OF THE BODY AND THE SLEEVE TOGETHER, A MANDREL CONNECTED TO SAID OTHER END OF THE BODY, ENGAGING SAID OTHER END OF THE SLEEVE, AND EMBRACING SAID SLEEVE FROM SAID OTHER END THEREOF TO A REGION THEREOF ADJACENT THE PORTION OF THE BODY IN WHICH THE SAID PASSAGES ARE LOCATED. 